In this paper, we propose a new feedback scheme called
mode selection-based feedback by scheduling probability prediction
(SPP-MF) for channel state feedback in OFDMA downlink
system. We design the scheme such that it determines the more
desirable feedback mode among selective feedback by scheduling
probability prediction (SPP-SF) mode and bitmap feedback
by scheduling probability prediction (SPP-BF) mode, by calculating
and comparing the throughputs of the two modes. In both
feedback modes, each user first calculates the scheduling probability
of each subchannel (i.e., the probability that a user wins the
scheduling competition for a subchannel) and then forms a feedback
message based on the scheduling probability. Specifically, in
the SPP-SF mode, each user reports the modulation and coding
scheme (MCS) levels and indices of its best S subchannels in terms
of the scheduling probability. In the SPP-BF mode, each user determines
its scheduling probability threshold. Then, it forms a
bitmap for the subchannels according to the scheduling probability
threshold and sends the bitmap along with the threshold. Numerical
results reveal that the proposed SPP-MF scheme achieves
significant performance gain over the existing feedback schemes.